The transformation of thermoplastic polyurethanes into polymeric foams is attracting great interest nowadays. However, this technology has some challenges that it is necessary to resolve, being one of the most important the shrinkage suffered by the polymeric foams over time. For that reason, this work explores several alternatives to mitigate this phenomenon. These alternatives are divided into two groups: on the one hand, the refoaming of the shrunken foams using supercritical CO and N was explored; on the other hand, the foaming using mixtures of supercritical CO and N as foaming agents was carried out. After experiments, it was seen that, the refoaming with N of shrunken foams obtained by supercritical CO technology can increase and keep constant the initial expansion ratio of the shrunken foams. Moreover, it was also observed that ratios of CO/N between 80/20 and 60/40 can avoid the shrinking issues suffered by the polymeric foams after foaming using supercritical technology.

中文翻译：

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使用超临界 CO2 和 N2 的热塑性聚氨酯发泡：防收缩策略


如今，热塑性聚氨酯向聚合物泡沫的转变引起了人们的极大兴趣。然而，该技术存在一些必须解决的挑战，其中最重要的挑战之一是聚合物泡沫随着时间的推移而遭受的收缩。因此，这项工作探索了几种减轻这种现象的替代方案。这些替代方案分为两组：一方面，探索了使用超临界 CO 和 N 对收缩泡沫进行再发泡；另一方面，使用超临界CO和N的混合物作为发泡剂进行发泡。经过实验发现，用超临界CO技术得到的收缩泡沫用N2再发泡，可以提高收缩泡沫的初始膨胀率并保持恒定。此外，还观察到CO/N的比例在80/20至60/40之间可以避免聚合物泡沫在使用超临界技术发泡后所遭受的收缩问题。